CLI::Helpers - Subroutines for making simple command line scripts


version 1.8


Use this module to make writing intelligent command line scripts easier.

    #!/usr/bin/env perl
    use CLI::Helpers qw(:all);

    output({color=>'green'}, "Hello, World!");
    verbose({indent=>1,color=>'yellow'}, "Shiny, happy people!");
    verbose({level=>2,kv=>1,color=>'red'}, a => 1, b => 2);
    debug_var({ c => 3, d => 4});

    # Data
    output({data=>1}, join(',', qw(a b c d)));

    # Wait for confirmation
    die "ABORTING" unless confirm("Are you sure?");

    # Ask for a number
    my $integer = prompt "Enter an integer:", validate => { "not a number" => sub { /^\d+$/ } }

    # Ask for next move
    my %menu = (
        north => "Go north.",
        south => "Go south.",
    my $dir = prompt "Where to, adventurous explorer?", menu => \%menu;

    # Ask for a favorite animal
    my $favorite = menu("Select your favorite animal:", [qw(dog cat pig fish otter)]);

Running as

    $ ./
    Hello, World!
    $ ./ --verbose
    Hello, World!
      Shiny, Happy people!
    $ ./ -vv
    Hello, World!
      Shiny, Happy people!
      a: 1
      b: 2
    $ ./ --debug
    Hello, World!
      Shiny, Happy people!
      a: 1
      b: 2
    c: 3
    d: 4

    $ ./ --data-file=output.csv
    Hello, World!
    $ cat output.csv

Colors would be automatically enabled based on the user's ~/.gitconfig


This module provides a library of useful functions for constructing simple command line interfaces. It is able to extract information from the environment and your ~/.gitconfig to display data in a reasonable manner.

Using this module adds argument parsing using Getopt::Long to your script. It enables pass-through, so you can still use your own argument parsing routines or Getopt::Long in your script.



This is called automatically when preprocess_argv is set. By default, it'll be run the first time a definition is needed, usually the first call to output(). If called automatically, it will operate on @ARGV. You can optionally pass an array reference to this function and it'll operate that instead.

In most cases, you don't need to call this function directly. It must be explicitly requested in the import.

    use CLI::Helpers qw( :output );

    # I want access to ARGV before CLI::Helpers;
    my %opts = get_important_things_from(\@ARGV);

    # Now, let CLI::Helpers take the rest, implicit
    #   call to cli_helpers_initialize()

Alternatively, you could:

    use CLI::Helpers qw( :output preprocess_argv );

    # Since CLI::Helpers opts are stripped from @ARGV,
    #  Getopt::Long::Descriptive won't complain about extra args
    my ($opt,$usage) = describe_option( ... );

    # Now, let CLI::Helpers take the rest, implicit
    #   call to cli_helpers_initialize()

Or if you'd prefer not to touch @ARGV at all, you pass in an array ref:

    use CLI::Helpers qw( :output );

    my ($opt,$usage) = describe_option( ... );

    cli_helpers_initialize([ qw( --verbose ) ]);

    verbose("you bet I am");


Not exported by default, returns the setting defined.


Not exported by default. Returns 1 if git is configured to output using color of 0 if color is not enabled.

colorize( $color => 'message to be output' )

Not exported by default. Checks if color is enabled and applies the specified color to the string.

output( \%opts, @messages )

Exported. Takes an optional hash reference and a list of messages to be output.

verbose( \%opts, @messages )

Exported. Takes an optional hash reference of formatting options. Automatically overrides the level parameter to 1 if it's not set.

debug( \%opts, @messages )

Exported. Takes an optional hash reference of formatting options. Does not output anything unless DEBUG is set.

debug_var( \%opts, \%Variable )

Exported. Takes an optional hash reference of formatting options. Does not output anything unless DEBUG is set.

override( variable => 1 )

Exported. Allows a block of code to override the debug or verbose level. This can be used during development to enable/disable the DEBUG/VERBOSE settings.


Exported. Creates a Yes/No Prompt which accepts y/n or yes/no case insensitively but requires one or the other.

Returns 1 for 'yes' and 0 for 'no'

text_input("prompt", validate => { "too short" => sub { length $_ > 10 } })

Exported. Provides a prompt to the user for input. If validate is passed, it should be a hash reference containing keys of error messages and values which are subroutines to validate the input available as $_. If a validator fails, it's error message will be displayed, and the user will be re-prompted.

Valid options are:


Any string which will be used as the default value if the user just presses enter.


A hashref, keys are error messages, values are sub routines that return true when the value meets the criteria.


Set as a key with any value and the prompt will turn off echoing responses as well as disabling all ReadLine magic. See also pwprompt.

Returns the text that has passed all validators.

Exported. Used to create a menu of options from a list. Can be either a hash or array reference as the second argument. In the case of a hash reference, the values will be displayed as options while the selected key is returned. In the case of an array reference, each element in the list is displayed the selected element will be returned.

Returns selected element (HashRef -> Key, ArrayRef -> The Element)

pwprompt("Prompt", options )

Exported. Synonym for text_input("Password: ", noecho => 1); Also requires the password to be longer than 0 characters.

prompt("Prompt", options )

Exported. Wrapper function with rudimentary mimicry of IO::Prompt(er). Uses:

    # Mapping back to confirm();
    my $value = prompt "Are you sure?", yn => 1;

    # Mapping back to text_input();
    my $value = prompt "Enter something:";

    # With Validator
    my $value = prompt "Enter an integer:", validate => { "not a number" => sub { /^\d+$/ } }

    # Pass to menu();
    my $value = prompt "Select your favorite animal:", menu => [qw(dog cat pig fish otter)];

    # If you request a password, autodisable echo:
    my $passwd = prompt "Password: ";  # sets noecho => 1, disables ReadLine history.

See also: text_input


This module uses Sub::Exporter for flexible imports, the defaults provided by :all are as follows.

Exported Functions

    output  ( \%options, @messages )
    verbose ( \%options, @messages )
    debug   ( \%options, @messages )
    debug_var ( \$var )
    override( option => $value )

    menu       ( "Question", \%Options or \@Options )
    text_input ( "Question", validate => { "error message" => sub { length $_[0] } } )
    confirm    ( "Question" )

    prompt()    Wrapper which mimics IO::Prompt a bit
    pwprompt()  Wrapper to get sensitive data

Import Time Configurations

It's possible to change the behavior of the import process.


Instead of messing with @ARGV, operate on a copy of @ARGV.

    use CLI::Helpers qw( :output copy_argv );

This causes the @ARGV processing to happen during the INIT phase, after import but before runtime. This is usually OK for scripts, but for use in libraries, it may be undesirable.

    use CLI::Helpers qw( :output preprocess_argv );

This causes the @ARGV processing to happen when the first call to a function needing it run, usually an output() call. This is the default.

    use CLI::Helpers qw( :output delay_argv );


From CLI::Helpers:

    --data-file         Path to a file to write lines tagged with 'data => 1'
    --tags              A comma separated list of tags to display
    --color             Boolean, enable/disable color, default use git settings
    --verbose           Incremental, increase verbosity (Alias is -v)
    --debug             Show developer output
    --debug-class       Show debug messages originating from a specific package, default: main
    --quiet             Show no output (for cron)
    --syslog            Generate messages to syslog as well
    --syslog-facility   Default "local0"
    --syslog-tag        The program name, default is the script name
    --syslog-debug      Enable debug messages to syslog if in use, default false
    --nopaste           Use App::Nopaste to paste output to configured paste service
    --nopaste-public    Defaults to false, specify to use public paste services
    --nopaste-service   Comma-separated App::Nopaste service, defaults to Shadowcat


This is optional and will only work if you have App::Nopaste installed. If you just specify --nopaste, any output that would be displayed to the screen is submitted to the App::Nopaste::Service::Shadowcat paste bin. This paste service is pretty simple, but works reliably.

During the END block, the output is submitted and the URL of the paste is returned to the user.


Every output function takes an optional HASH reference containing options for that output. The hash may contain the following options:


Add a keyword to tag output with. The user may then specify --tags keyword1,keyword2 to only view output at the appropriate level. This option will affect data-file and syslog output. The output filter requires both the presence of the tag in the output options and the user to specify --tags on the command line.

Consider a script,

    output("System Status: Normal")
    output({tag=>'foo'}, "Component Foo: OK");
    output({tag=>'bar'}, "Component Bar: OK");

If an operator runs:

    System Status: Normal
    Component Foo: OK
    Component Bar: OK

    $ --tags bar
    System Status: Normal
    Component Bar: OK

    $ --tags foo
    System Status: Normal
    Component Foo: OK

This could be helpful for selecting one or more pertinent tags to display.


Any lines tagged with 'sticky' will be replayed at the end program's end. This is to allow a developer to ensure message are seen at the termination of the program.


String. Using Term::ANSIColor for output, use the color designated, i.e.:

    red,blue,green,yellow,cyan,magenta,white,black, etc..

Integer. For verbose output, this is basically the number of -v's necessary to see this output.


String. Can be any valid syslog_level as a string: debug, info, notice, warning, err, crit, alert, emerg.


Bool. Even if the user specifies --syslog, these lines will not go to the syslog destination. alert, emerg.


Bool. Even if --quiet is specified, output this message. Use sparingly, and yes, it is case sensitive. You need to yell at it for it to yell at your users.


Bool. Use STDERR for this message instead of STDOUT. The advantage to using this is the "quiet" option will silence these messages as well.


Integer. This will indent by 2 times the specified integer the next string. Useful for creating nested output in a script.


Integer. The number of newlines before this output.


Bool. The array of messages is actually a key/value pair, this implements special coloring and expects the number of messages to be even.

    output(qw(a 1 b 2));
    # a
    # 1
    # b
    # 2

Using kv, the output will look like this:

    output({kv=>1}, qw(a 1 b 2));
    # a: 1
    # b: 2

Bool. Lines tagged with "data => 1" will be output to the data-file if a user specifies it. This allows you to provide header/footers and inline context for the main CLI, but output just the data to a file for piping elsewhere.


Brad Lhotsky <>


This software is Copyright (c) 2020 by Brad Lhotsky.

This is free software, licensed under:

  The (three-clause) BSD License


  • Kang-min Liu <>

  • Kevin M. Goess <>

  • Mohammad S Anwar <>



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Source Code

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